On not logging things
One of the machines I help look after is an open, read-only Usenet server (details here; the open access is a 'because we can' thing). You might be surprised to know that the server logs only minimal information about NNTP sessions, and this is a deliberate action that required hacking the software a bit.
When I was setting up the machine and planning open access for everyone on campus, I found myself thinking about how I'd feel if, for example, some day a department head came to us to say 'I want to know what newsgroups people in my department are reading'. Much like library borrowing records, what newsgroups people read can be embarrassing or damaging; did I really want to be in a position of turning over that information?
As system administrators, we often default to logging everything we can that doesn't expose obvious security risks. But this opens up more subtle abuses and risks (especially as people seem much more willing to go snooping through computer logs than other records, perhaps because computer logs are seen as 'less private').
So I'd like to urge sysadmins to consider the merits of not logging things. Consider if you really need to know that piece of information, or whether you're hoovering it up just because.
(The issue is not new with computers; librarians have been dealing with this for a long time and take it quite seriously.)